Technical Field
The invention relates to the technical sector of gearboxes for motor vehicles and especially concerns a device for detecting the position of a control lever.
Description of the Related Art
Note that for a person skilled in the art, it is common knowledge that the lever is assembled with the capacity for angular displacement in a support housing that is normally fixed in the cab interior of the vehicle. The lever is arranged such that, for example, it is coupled to a system of cables to ensure gears selection control and shifting, either in the case of an automatic transmission or in the case of a mechanical transmission. Knowing the angular position of the lever and its precise spatial position is important for knowing the position of the lever in neutral, especially for vehicles fitted with a STOP and START system normally associated with a manual transmission.
Different solutions have been put forward to perform this function. For example, we can cite the information given in patent FR 2930309, the applicant of which is also the owner, and which pertains to a device for detecting the position of the control lever, which is assembled with the ability to move contrary to the means that are capable of detecting the angular movements of the lever and to send electrical signals to a processing unit. These means comprise a single Hall Effect Sensor fitted opposite a magnet, capable of indicating the different movements and positions of the lever according to the three perpendicular axes X, Y and Z.
A solution of the same type is given in the information of patent FR 2956177, which is also held by the applicant of this patent, according to which the means of detecting the angular movement of the lever comprise a cylindrical magnet for axial magnetization, positioned according to the rotation axis of the lever corresponding to the gear selection, and a sensor placed opposite the said magnet such that the signal remains independent of the position of the lever according to the gear selection axis.
It therefore follows from this state of the art, given for information purposes and in no way limitative, that the position of the lever is detected by measuring the angular movements of the said lever.
According to the state of the art, there is another possibility of measuring the linear movements of the lever, rather than its angular movements. In fact, the gear shifting movements correspond to the exact translations of, for example, the ends of the cable/sheath pair, e.g., between an end piece of a cable and an end piece of a cable and an end piece of a sheath. One of the advantages of this linear movement measurement is that it determines both movements (shifting and selection) differently, which makes it possible to measure only one of them, e.g., only the selection movement is required for detecting the neutral.
The possibility of detecting a linear movement is, for example, given in the patent EP 2078886, which concerns a transmission control device, in particular for the transmission of a motor vehicle, with a system for identifying the selected gear. According to the information given in this patent, the proposed solution involves the use of a specially designed linear position sensor in order to detect the linear position of a mobile reference element that is rigidly connected to monitor a translation movement with, for example, an end piece of a cable. This solution is relatively complex as it requires, as indicated, a specific linear position sensor, while also requiring relatively significant space, which is not always compatible with the environment of a gearbox.
The EP 1096177 patent provides general information on the detection of linear movement by a cable and a sheath using an electrical sensor that is formed by multiple coils wound around a support. However, this patent does not give any information on the manner in which such a movement is detected.
From this state of the art, the problem that this invention seeks to solve is to use magnetic technology with the purpose of detecting the linear position of a transmission member such as a cable connected to the lever in order to detect the position of the said lever, at least one of the ends of the transmission member being connected to a fixed end piece sliding into an end piece of a fixed sheath.